Technical measures for lightning protection of the

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Technical measures for lightning protection of substation

1 sources and solutions of lightning stroke in substation

substation is an important protection facility for lightning protection of power system. In case of lightning stroke accident, it will cause a large area of total investment. 19 all seamless steel pipes will be subject to mechanical property test. 900million yuan of power failure will seriously affect the society and people's life. Therefore, the lightning protection measures of the substation must be very reliable. ① Source of lightning strike. First, lightning strikes the equipment of the substation directly; Second, the lightning wave formed by lightning induced overvoltage and direct lightning overvoltage of overhead lines invades the substation along the line. ② The protection of substation against direct lightning strike is generally solved by installing lightning rod or erecting lightning wire within a certain distance along the incoming line of substation. ③ The lightning wave formed by lightning induced overvoltage and direct lightning overvoltage of overhead lines intrudes into the substation along the line, which is the main cause of lightning damage in the substation. If lightning protection measures are not taken, the insulation of electrical equipment in the substation will be damaged and accidents will be caused. The purpose of installing lightning arrester in substation is to limit the amplitude of invasion lightning wave, so that the overvoltage of electrical equipment will not exceed its impulse withstand voltage value. The main purpose of installing protection section on incoming line of substation is to limit the amplitude of lightning current flowing through lightning arrester and the steepness of invasion lightning wave

2 principle of installing lightning rod in substation

all protected equipment shall be within the protection range of lightning rod (line) to avoid lightning stroke. When lightning strikes the lightning rod, the potential of the lightning rod against the ground may be very high. If the insulation distance between them and the protected electrical is not enough, it may cause discharge between the lightning rod and the protected equipment after lightning strikes. This phenomenon is called counterattack. At this time, the lightning rod can still add the high potential of lightning wave to the protected electrical equipment, causing accidents

3 determination of minimum lightning protection distance between lightning rod and electrical equipment

when lightning rod strikes, lightning current flows through the lightning rod and its grounding device. In order to prevent the air gap between the lightning rod and the protected equipment or framework from being broken down and causing a counterattack accident, the air gap must be greater than the minimum safety clearance

4 relevant provisions for installing lightning rods

for 35kV and below substations, due to their low insulation level, independent lightning rods must be installed to meet the requirements of no counterattack. For substations above 110KV, due to the high insulation level of distribution devices with such voltage levels, lightning rods can be directly installed on the framework of distribution devices. Therefore, the high potential generated by lightning rods will not cause electrical equipment counterattack accidents. The distribution frame equipped with lightning rod shall be equipped with auxiliary grounding device. The electrical distance between the grounding device and the grounding point of the substation shall not be less than 15m from the grounding device of the main transformer and the grounding point of the substation. Its function is to make the high-voltage mutual pollution position generated on the grounding device of the lightning arrester gradually attenuate in the process of propagating along the grounding to the grounding point of the transformer, so that the invaded lightning wave is beneficial to solving its performance of water absorption and nail nailing; When the transformer is grounded, it will not cause the counterattack accident of the transformer. As the insulation of the transformer is weak and the transformer is an important equipment of the substation, the lightning rod shall not be installed on the door frame of the transformer. Since the distance between the power distribution device of the substation and the first tower of the substation outgoing line may be relatively large, if it is allowed to lead the lightning conductor on the tower to the framework of the substation, this section of conductor will be protected, which is more economical than using lightning rod. Due to the shunt effect at both ends of the lightning conductor, the potential rise caused by lightning stroke is smaller than that caused by the lightning rod. Therefore, the 110kV and above power distribution devices can lead the line lightning conductor to the outgoing gate frame, but the areas with soil resistivity greater than 1000 m should be installed with centralized grounding devices. For 35 ~ 60kV power distribution devices, in the area where the soil resistivity is not greater than 500 m, it is allowed to lead the lightning conductor of the line to the outgoing gate frame, but a centralized grounding device shall be installed. When the soil resistivity is greater than 500 m, the lightning conductor shall terminate at the line terminal tower, and the first gear line protection of the incoming substation can be protected by lightning rod

the mechanism of lightning is very complex. We can not fully control the occurrence of lightning damage, but we can reduce the occurrence of lightning damage through necessary lightning protection measures. In order to ensure the safe operation of electricity, we should constantly sum up experiences and lessons, strengthen the work of operation, overhaul and maintenance, pay attention to lightning protection countermeasures and technical transformation, and take targeted preventive measures

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